Conversion of nonbenzenoid hydrocarbons to aromatics



Patented June 8, 1943 CONVERSION OF NONBENZENOID HYDRO- CARBONS TOAROMATICS Robert E. Burk and Everett 0. Hughes, Cleveland Heights, Ohio,assignors to The Standard Oil Company, Cleveland, Ohio, a corporation ofOhio No Drawing. Original application March 21, 1939, Serial No.263,198. Divided and this application October 19, 1939, Serial No.300,238

3 Claims.

In the catalytic treatment of carbon-containing compounds, such asalcohols, hydrocarbons, etc., and particularly hydrocarbons, where thecatalyst is of oxide type, a serious practical diificulty has been thetendency of the catalyst to coke up, thereby shortening the possiblerun, and adding to the difficulty of regenerating or cleaning, and evenafter regeneration has been effected to the greatest extent possible,the catalyst tends to lack a desirable standard of emciency. We havefound however that by providing catalyst compositions of the peculiarcharacter set forth in detail below, the surprising result occurs that acatalyst does not tend to rapidly coke up such as in the case of theknown oxide catalysts, and it regenerates more readily and provides higheificiency as regenerated.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described, andparticularly pointed out in the claims, the following descriptionsetting forth in detail certain illustrative embodiments of theinvention, these being indicative however, of but a few of the variousways in which the principle of the invention may be employed.

In accordance with the invention, the catalysts, of oxide character, areprepared such as to contain oxide of copper, this being in minor amountfor the whole composition, and desirably where the catalyst is to beapplied for aromatizing or dehydrogenating hydrocarbons, the othercomponents may be oxides of aluminum and chromium. Whilecopper-containing compositions maybe employed in which the proportionsof the other components vary considerably, it is preferable thataluminum oxide be in the range of 42.5-88.2 mol per cent, and chromiumoxide in the range of 8.5-49 mol per cent, and the copper oxide 2-15 molper cent and insofar as efiective activity for such operations asaromatizing and dehydrogenating are concerned these ratios are rathercritical. The compositions may be made by mixing copper oxides withchromium and aluminum oxide; by adsorbing or precipitating copper oxideon the surface of the chromium and aluminum oxide; or the copperconstituent may be co-precipitated with the aluminum and chromiumconstituents by pouring solutions together, or better by stagewiseprecipitation, in which precipitating action is first carried on with aninsufiiciency of the precipitant, and then as a second stage enoughprecipitant is brought into action to complete the precipitation.Gaseous and aqueous ammonia are especially desirable in this form ofdual action. The catalyst is washed free of ammonia salts by decantationor preferably by filtration, and is dried in suitable manner. Thecatalyst may be dried by spreading out a thick layer and passing heatedair over it, after which it may be broken up and screened. A furtherstep of drying at elevated temperature, e. g. 400 F. or higher, with orwithout a vacuum is particularly desirable. v

As illustrative of the preparation of the catalyst, the following may benoted:

I. 28 parts by weight of an oxide catalyst material containing mol percent to 20 mol per cent of the oxides of aluminum and chromiumrespectively, are moistened with 10 parts of a solution containing 2.43parts of Cu(NO3)2.3H2O, Ammonia gas is then applied to precipitate thecopper. The catalyst is then washed and dried.

II. 125 per cent of a theoretical precipitating amount of ammoniumhydroxide is poured into 3,000 parts of a solution containing parts ofammonium acetate together with nitrates of aluminum, chromium and copperin proportions to furnish 78 mol per cent A1203, 20 mol per cent C1'2O3,and 2 mol per cent CuO. The mixture is allowed to stand about two hours,and it is then filtered and washed by filtration and dried.

III. By stage-wise precipitation, there is fed to a mixing zone 600parts per minute of a solution containing 960 parts by weight ofammonium acetate, 6.24 mol aluminum nitrate, 1.6 mol of chromiumnitrate, and 0.16 mol of copper nitrate per each 48,000 parts ofsolution, the mixing zone having a capacity of 600 parts of liquid, andgaseous ammonia is fed in, to '70 per cent neutralization, the overflowfrom this mixing zone proceeding to another mixing zone in which thesolution is then further mixed with ammonium hydroxide at the rate of680 parts concentrated NH4OH to each 16,000 parts of water and is fed atthe rate of 200 parts per minute. The liquid proceeding from the secondmixing zone is filtered at a rate substantially even with theprecipitation rate. The catalyst is washed and dried.

In operation for instance in aromatizing hydrocarbons, these catalystsare active at temperature of 750-1250 F., and pressures of atmosphericup to about 400 pounds per square inch may be used. Hydrogen or part ofthe off-gases recycled may be used to dilute the feed hydrocarbons,which are supplied in vapor iorm. Thus,'a catalyst of oxides of copperand aluminum and chromium in proportions of 2 mol and 78 mol and mol percent respectively, operating on naphtha from Michigan petroleum, withoperating conditions of 932 F. and flow rate or 1 volume of liquidhydrocarbon per hour per volume of catalyst, yielded a product having aKattwinkel test oi. 50 per cent. Again, a simflar catalyst operating onre-run naphtha bottoms with similar operating conditions, gave a producthaving a Kattwinkel test of 67 per cent.

And in general, aliphatic hydrocarbons or paraflins and olefins andnaphthenic hydrocarbons, naphthas, and distillates and non-benzenoidhydrocarbon stocks may be employed. It is of particular advantage forinstance to fractionally divide a distillate into light and heavierportions or cuts, and subject these to the action of the catalyst, andthen crack the heavier portion or cut, catalytically or thermally. It isdesirable also to treat the product from the catalytic zone byseparating aromatics formed, as for instance by a selective solvent suchas liquid sulphur dioxide or of high boiling amine or a phenol, andre-pass the undissolved or non-benzenoid portion into contact with thecatalyst. In general, the feed rates of the hydrocarbon to the catalystmay be 0.1 to 10 gallons per hours per gallon volume of catalyst.

These catalysts may be regenerated by subjecting to the action ofoxygen-containing gas, such as air, or air diluted with nitrogen forinstance, and the temperature of regeneration may be 750-1100 F. Thecarbon dioxide formed in such regeneration may be employed for heatingthe catalyst bed. It is remarkable that the present catalyst is not onlyregenerated readily, but continues to show little coke formation andeven less than on the original catalyst.

This application is a division of our application Serial No. 263,198,filed March 21, 1939, now Patent No. 2,280,060; issued April 21, 1942.

Other modes oi. applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

We therefore particularly point out and distinctly claim as ourinvention:

1. A process of converting hydrocarbons to aromatics, which comprisessubjecting nonbenzenoid hydrocarbonsto the action of a contact masscharacterized by 2-15 mol per cent of copper oxide with 42.5-88.2 mm percent of gel type aluminum oxide which is co-precipitated with -49 molper cent of chromium oxide, at 700-1250 F.

2. A process of converting hydrocarbons to aromatics, which comprisessubjecting nonbenzenoid hydrocarbons to the action of a contact masscharacterized by 2-15 mol per cent of copper oxide .with 42.5-88.2 molper cent of gel type aluminum oxide which is co-precipitated with 8.5-49mol per cent of chromium oxide, at 700-1250 F., separating aromaticsfrom the product, and recontacting the non-benzenoid hydrocarbons of theproduct with the contact mass.

3. A process of converting hydrocarbons to aromatics, which comprisessubjecting a petr0- leum distillate containing non-benzenoidhydrocarbons to the action of a contact mass characterized by 2-15 molper cent of copper oxide with 42.5-88.2 mol per cent of gel typealuminum oxide which is, co-precipitated with 85-49 mol per cent ofchromium oxide, at 700-1250 F. and flow rate of 0.1-10 vol. of liquidper hour per vol. of contact mass.

ROBERT E. BURK. EVERETT C. HUGHES.

